Decolorization and MIneralization of Methylene Blue in Aqueous Solutions by Persulfate/Fe2+ Process

Autor: Saeid Ildari, Mostafa Mahdavianpour, Mehrdad Moslemzadeh, Mehdi Ebrahimi
Rok vydání: 2020
Předmět:
Zdroj: Journal of Water Chemistry and Technology. 42:244-251
ISSN: 1934-936X
1063-455X
Popis: Today, the treatment of dye wastewater discharged by various industries, such as textiles, has attracted the attention of many researchers due to the non-biodegradability nature of dye contaminants. Methylene blue is one of numerous dyes existing in this wastewater that causes a variety of human health problems. Because of the low efficiency of biological treatment processes in the removal of this range of contaminants, physicochemical technologies such as adsorption and advanced oxidation processes have been studied as efficient alternatives. Among them, advanced oxidation processes can provide almost complete removal of these contaminants with the least requirement to manage final products. In these processes, the objective is the production of reactive radicals (such as $$^{\centerdot }{\kern 1pt} {\text{OH}}$$ and $${\text{SO}}_{4}^{{\centerdot - }}$$ ) which are suitable for rapid and non-selective reactions with organic contaminants. So, in this study, decolorization and mineralization of methylene blue in aqueous solutions were investigated by the persulfate/Fe2+ process. For this purpose, the effect of different parameters such as pH, per-oxydisulfate/Fe2+ ratio, peroxydisulfate concentration, and initial methylene blue concentration were evaluated. In addition, predominant radicals and mineralization of methylene blue were studied. Finally, the contribution of each sub-process and degradation of methylene blue in real wastewater were investigated. In the first step of this study, the effect of initial pH on methylene blue removal by persulfate/Fe2+ process, it was observed that with increasing pH from 3 to 9, the removal efficiency of 50 mg/L of methylene blue was decreased from 84.4 to 69.7%. In the second step, obtained results showed that with increasing peroxydisulfate/Fe2+ ratio from 2 to 16, methylene blue removal efficiency was decreased to 18%. The supplementary experiments for determination of predominant radicals using tert-butanol and methanol revealed that sulfate radical was predominant in the applied process. Although complete decolorization of methylene blue was attained at 20 min, when the time lasted to 40 min, 96% mineralization of methylene blue was observed by peroxydisulfate/Fe2+ process. Finally, the studied process showed efficient removal of methylene blue dye from aqueous solution and real wastewater containing a high concentration of methylene blue.
Databáze: OpenAIRE
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